Would somebody be willing to help me troubleshoot this problem with DeviceAgentException?

This is my first project with Xamarin and UITest and I have been able to get the UITest project up and running on my own so far and have been able to fix most of my problems. But this one has me at a loss. My tests had been running and executing fine locally until last week when I started working on trying to get some tests to run via command line. I ran an msbuild script to build the project which built fine. But after that (not sure if it had anything to do with it) my tests would not run locally. Test results come back with the following error:

Calabash.XDB.Core.Exceptions.DeviceAgentException : Unable to contact DeviceAgent
  ----> System.AggregateException : One or more errors occurred.
  ----> Calabash.XDB.Core.Exceptions.DeviceAgentException : Unable to contact DeviceAgent on 127.0.0.1
  ----> System.MissingFieldException : Field 'System.Net.HttpWebRequest.ResendContentFactory' not found.

The project is a Xamarin.Forms (6.1.2 b44) project with iOS and Android builds. I am running Xcode 8.2
I have tried deleting the xdb folder and running to no avail.

Any help is greatly appreciated!